For a Low Load Sliding Intermediate Shaft in a Steering Column for Industrial Vehicles

ABSTRACT

The invention refers to improvements to the intermediate shaft in the claims of the main patent to adjust the depth of the steering wheel to match the driver&#39;s measurements, to absorb vibrations which may be generated by the wheels and suspension up to the steering wheel, as well as acting as a safety measure to collapse in the event of an accident which may also be by using the corresponding screw/nut mechanisms comprising a nut rigidly connected to the intermediate shaft on one of the flat surfaces of the female shaft and a screw which turns on it tightening the male shaft via the adjustment spring, so that it gently slides (with a predetermined load deemed to be suitable for facilitating sliding it by hand).

More specifically, the invention refers to improvements to theintermediate shaft in the claims of the main patent to adjust the depthof the steering wheel to match the driver's measurements, to absorbvibrations which may be generated by the wheels and suspension up to thesteering wheel, as well as acting as a safety measure to collapse in theevent of an accident which may also be by using the correspondingscrew/nut mechanisms comprising a nut rigidly connected to theintermediate shaft on one of the flat surfaces of the female shaft and ascrew which turns on it tightening the male shaft via the adjustmentspring, operating in the following manner:

-   -   When the screw is not tightened, the male shaft gently slides        (with a predetermined load deemed to be suitable for        facilitating sliding it by hand) so that the operator who is        working on the line to raise the column, is able to extend it        without great effort, thereby facilitating vehicle assembly work        using its steering pinion and/or the steering column.    -   Once the steering column has been assembled, the screws are then        tightened so that the above sliding joint becomes a strong joint        giving the steering system great torsional and hysteresis        rigidity, due to the action of the force that the screw applies        in the direction of its axis and due to the reaction of the        triangular faces on the female shaft onto which the force is        exerted.

The mechanism which is built into the intermediate shaft shall includeas a minimum, a nut which, due to its intrinsic function it plays on theintermediate steering shafts, has to be safe and be able to operate withdifferent coverings guaranteeing its function and aspect againstunwanted environmental effects so that corrosion and/or loss ormechanical or chemical properties in the materials are avoided and/orguaranteeing the appearance requirements which may be required by thecustomer.

As stated in the above paragraph, the nut has to be safe, ensuring itsperfect operation without it affecting the complete full of the screw.In order to do this, the nut may be, although not limited to, oval, witha plastic retainer, or similar, so that any unexpected loosening of thescrew inserted into it is avoided. This function is only taken intoaccount when there is no locking feature on the screw.

Similarly, the mechanical features and dimensions of the nut have toensure that the thread safety ensures the above mentioned safetyfunction with the properties of the screw lodged into it, with, as ageneral rule, the improved quality of the same.

If the dimensional characteristics of the thread are significant, theexternal properties are not so significant, with the nut being in themost suitable external shape and size (hexagonal, cylindrical, square orsimilar), to minimize the turning diameter of around the intermediateshaft.

The form of fixing the nut onto the flat surface of the female shaftforming part of the intermediate shaft, the joint between the nut andshaft has to be rigid, without this being limited to the method used toachieve this. Therefore, for example, welding, pinning the nut orencapsulating it without denigrating any other method, may be acceptablefor achieving the required aim, that is to say the rigidity andconsistency of the nut/female shaft joint.

One of the surfaces of the female shaft has to be prepared so that,firstly, depending on the way the nut is held, it is able to house thenut. Therefore, for example, this shall not be the same in the eventthat the nut is welded, which requires no previous preparation to theshaft, rather than the pinned nut, which shall require a calibrateddiameter, or the encapsulated nut which shall require holding by thecage itself. Secondly, the female shaft has to be perforated, by anymethod (drilling, punching or other) so that it allows the screw to passthrough it to fulfil its tightening function on the male shaft againstthe two triangular faces of the female shaft.

It has to be highlighted that the function of the screw is safety, withit being equipped with the means required to prevent it from looseningduring the vehicle's assembly. In order to do this, without detriment tothe possible use of any other method, any method available on the marketmay be used, such as, the trilobular system, sealed with nut holders orsimilar.

Notwithstanding the above, the shape of the screw head, where thescrewdriver is applied, may be different, such as, hexagonal, Allen,Phillips or other, wherever these ensure the tightening torque not onlyfor the operator, but also for the integrity of the tool applying thetorque and for the screw itself, both on the head and on the thread.

As stated previously for the nut, the dimensional and materialproperties of the screw have to be appropriate for the torque to beapplied and for the application of the same, with the quality andproperties of the thread being the most appropriate.

Similarly, to determine the length of the screw, the diameter of theturning circle for the intermediate shaft has to be taken into accountonce the screw has been inserted into the nut holding it. It has to beemphasized that, as the turning has to be very limited, normally lessthan one turn, and due to the fact that it only has to move axiallyalong the distance required to adjust it, which usually is less than thepassage of the screw, the length of the same may actually be very short.

The advantages of the improvements described with the low loadintermediate shaft in the main patent no. 200400175, are being able tocombine an easy movement of the said axis, in the first part of thecolumn assembly, when the screw is loose, for the shaft assembly withtorsional and hysteresis rigidity (due to the subsequent tightening ofthe screw holding the slide.

Alternatively, another of the aims of this improvement, there is theoption of converting the intermediate shaft into a sliding shaft withthe option to adjust the sliding load and the torsional and hysteresisrigidity achieved by the increased or decreased axial movement of thescrew as a consequence of the greater or lesser turning angle appliedduring its tightening to torque. This shall be of great use in the eventthat the shafts requiring to slide although with a great load, as iscommon in 4×4 vehicles and height adjustable columns where the pivotingpoint does not coincide with the centre of the universal joint on thecolumn connection or, if not, when this universal joint moves spatiallydue to the adjustment movements

Moreover, the application of a sliding, triangular, intermediate shaftallows, because of the force of the screw applied to the opposingtriangular faces, perfect adjustment that, even though possible, is noteasy to achieve with shafts with other cross sections, whether these arecircular (grooved or otherwise), double D shaped, right angled and othershapes, so that it safely and reliably prevents the play which ischaracteristic of intermediate shafts.

It is also appropriate to state that another of the these improvementsin this configuration is the absence of noise caused by the effects ofresonance which, being caused by parts outside the steering system,usually appear in the intermediate shaft as this is the weakest part ofthe chassis and bodywork joint. This improvements change the rigidity ofthe intermediate shaft, modifying the resonance frequency of the sameand making noise inaudible which, in another way, appear in the system.

Field trials performed to check the suitability of these improvements onthe environmental properties, to indicate its suitability in every typeof temperature and operating conditions, the improvement is not in theshaft situation but in the engine section or in the passengercompartment.

Finally, the excellent behaviour with regard to wear has to behighlighted making this configuration ideal for intermediate shaftssubjected to significant and demanding operating life and fatiguerequirements. The possibility of adjusting the screw with a simpleservicing operation allows the worn intermediate shaft, and thereforewith its rigidity and angular play properties, to become a shaft withsimilar properties, if not the same properties as a new intermediateshaft.

Other details and characteristics shall be shown throughout thedescription below referring to drawings attached to this reportdemonstrating the main properties of the invention without the samebeing solely restricted to it.

Below is a list of the main parts in the invention which are shown indiagrams attached to this report; (10) intermediate shaft, (11) femalepart, (12 and 13) universal joint, (14) male part, (15) metal strip,(16) holding cage, (17) holding cage compartments, (18) screws, (19)nuts, (20) drilled holes, (21) openings, (22) shaft face (4), (23) screwbase (18), (24) beveling.

FIG. 1 is a front elevation view of the intermediate shaft (10), thesubject of these improvements in which the male shaft (14) is partiallyplaced into the female shaft (11), on one of the ends of (11-14) theuniversal joints (12-13).

FIG. 2 is a rotated view compared to FIG. 1 with regard to thelongitudinal shaft crossing (10) longitudinally.

FIG. 3 is a detail “1” according to FIG. 2.

FIG. 4 is a partial elevation view of the described intermediate shaft(10).

In one of the preferred implementations of these improvements as shownin FIGS. 1 and 2, the recommended improvements concentrate on theinclusion on a female shaft (11) on the intermediate shaft (10) of someopenings (21), on at least one of the faces allowing the assembly of amechanism formed by a nut (19) and a screw (18), with the latter passingthrough a drilled hole (20) in the nut (19).

FIG. 3 shows detail “1” according to FIG. 2, demonstrating how the bases(23) of the screw (18) rest on the upper surface of the metal strip (15)inserted in the cage (16), the rear of which (15) is in contact with themale shaft (14).

The nut (19) has been designed with a small lower bevel (24) which issupported on the opening (21).

Increased pressure on the bases (23) of the screws (18) on the metalstrip (15), causes more or less retaining strength of shaft (14) withregard to shaft (11), in the assembly position of the steering columnwith the bases (23) not being in contact with the male shaft (14) andmore specifically with the surface of the strips (15), depending on theloads required in each case, allowing the calculation of different basevalues to join more than two screws (18), as well as changing themagnitude of the base surface (23), its roughness and the distancebetween the screws (18) within the female shaft (11), so that it will bepossible to attain values consistent with the loads which each carmanufacturer assigns to the manufacture of the steering column.

Therefore without any need for applying the mechanism to more than oneface (22) of the male shaft (14), the force of the screws (18) istransferred to the other metal strips (15), an effect produced as aconsequence of the initial design of the transverse section of thetriangular intermediate shaft.

Having sufficiently described this invention using the figures attached,it is easy to understand that any changes judged to be suitable may bemade, whenever these changes do not alter of the essence of theinvention summarised in the following claims.

1. “IMPROVEMENTS TO PATENT No. 200400175 FOR A LOW LOAD SLIDINGINTERMEDIATE SHAFT IN A STEERING COLUMN FOR INDUSTRIAL VEHICLES”including a female element designed to house a male part by sliding itinto it and at least one strip mounted between the same which has anirregular contact surface and that these strips are assembled betweenthe male part and the female part and inside some housings for a holdingcage which in turn is firmly attached to the external surface of theaforementioned male part, with the cage being solidly attached to theoutside of the male part using ridges in its external surface, with thiscage being located on the male part characterized by the fact that thestrips (15) located on the cage (16) are pressed on by safety screws(18) and its bases (23) which cross the female shaft (11) by openings(21) in at least one of the faces of the female faces (11) by theintrinsic function of the intermediate shafts in vehicle steering havingto be safe and, the threading and unthreading of these screws on safetynuts (19) resting on a lower bevel (24) on these openings (21). 2.“IMPROVEMENTS TO PATENT No. 200400175 FOR A LOW LOAD SLIDINGINTERMEDIATE SHAFT TN A STEERING COLUMN FOR INDUSTRIAL VEHICLES”according to claim 1, wherein the sliding load the male shaft (14) withregard to the female shaft (11) and the rigidity and hysteresischaracteristics of the intermediate shaft (10) depend on the number ofscrews (18) and the tightening applied to the shaft (11). 3.“IMPROVEMENTS TO PATENT No. 200400175 FOR A LOW LOAD SLIDINGINTERMEDIATE SHAFT IN A STEERING COLUMN FOR INDUSTRIAL VEHICLES”according to claim 1, wherein the sliding load the male shaft (14) withregard to the female shaft (11) and the rigidity and hysteresischaracteristics of the intermediate shaft (10) depend on the distancebetween the screws (18) in the shaft (11).
 4. “IMPROVEMENTS TO PATENTNo. 200400175 FOR A LOW LOAD SLIDING INTERMEDIATE SHAFT IN A STEERINGCOLUMN FOR INDUSTRIAL VEHICLES” according to claim 1, wherein thesliding load the male shaft (14) with regard to the female shaft (11)and the rigidity and hysteresis characteristics of the intermediateshaft (10) depend on the surface of the base (23) of the screws (18).